EP0968058B1 - Method and device for coating a substrate to provide it with antiadhesive properties, using a cross-linkable silicon composition - Google Patents

Abstract

Coating support strip in order to give it anti-adherent properties is carried out with the aid of a silicone composition containing at least one polyorganosiloxane (A) and at least one crosslinking agent (B), and which is crosslinked by hydrosilylation and/or dehydrogenation polycondensation, in presence of catalyst (C). Method comprises: 1) continuous mixing of compound(s) (A), which have reactive groups, compound(s) (B), which have reactive groups, and (C) to produce at least one pre-mixture (AB) and/or (AC) and/or (BC) whichever is easiest; 2) forwarding mixture to coating site; 3) coating strip; and 4) crosslinking product. Time spent in water bath is preferably 2 hours. Bath provides heating profile (Gaussian) with temperature T1 at start of peak, T2 at top of peak, and T3 at end of peak , such that T3 preferably = 80[deg]C, and T3-T1 = 15[deg]C and mid peak width is +- 4[deg]C. The rate of production of the mixture is such that the time spent in separating it and apply ing the coating is at most the time spent in bath. Also claimed are device for carrying out said method; and silicone composition produced by it.

Description

The field of the present invention is that of the compositions silicones crosslinkable by activation, which can be used in particular for forming a coating or an anti-adherent film for fiber support or not, by example paper or the like, or even natural polymer or synthetic.

More specifically, the invention relates to a coating process in continuous movement of a strip of moving support (e.g. paper, fabric, polymer), with a view to to give it anti-adhesive properties, said coating being carried out using a silicone composition based on polyorganosiloxane (POS).

The anti-adherent POSs we are interested in as part of the invention are of the type of those crosslinkable, by hydrosilylation or by dehydrogenopolycondensation, thermally or by association of the heat and radiation (UV radiation or electron beam).

More specifically, the POS considered are for example those that can be crosslinked quickly ("fast cure") and at low temperature ("Low Temperature Cure ") -POS FC / LTC.

The present invention also relates to the device and the silicone composition involved in the continuous coating process, which is its main purpose.

Conventionally, the silicone anti-adherent compositions, comprise at least one POS A, a crosslinker B which is a POS and a catalyst. These ternary compositions can only exist ephemeral in the uncrosslinked state. Indeed, whatever the crosslinking mechanism concerned: hydrosilylation or dehydrogenopolycondensation, POS type SiH brought together in the first case of SiVi-type POS and catalyst platinum hydrosilylation or in the second case of SiOH or SiOR type and platinum or tin condensation catalyst reticulate more or less quickly. The crosslinking speed depends especially the reaction temperature.

Moreover, it should be recalled that the SOPs constituting anti-adherent compositions may be present, in the uncrosslinked state, in the pure or in the form of crosslinkable liquid solutions or emulsions.

It follows that for the non-stick treatments of media (paper, cloth or polymer film), which consists in coating the surface of these supports with the aid of above-mentioned silicone compositions, it is imperative to perform the application and spreading said compositions when in liquid non-crosslinked form and therefore all in fact suitable for the said operations.

Once the supports are coated with silicone composition, they are subjected to heating so as to accelerate their crosslinking.

In view of the foregoing, we can easily see two difficulties, among others, which will arise as soon as treatment is considered anti-adhesion by silicone coating e.g. of thermoplastic paper or film, at a rate and on an industrial scale.

The first difficulty is that silicone systems (putting use of pure POS, emulsion or solvent phase ...) crosslinking thermally and which are usually used, require temperatures between 100 and 200 ° C. It is clear that at these temperatures, it is is difficult, if not impossible, to consider the coating of certain media such as thermoplastic films such as polyethylene, polypropylene, PVC and to a lesser extent, polyethylene glycol terephthalate. These systems silicones are further characterized by DVB bath lifetimes greater than or equal to 10 hours and, in practice, between 12 and 24 hours.

DVB refers to the time required to double the dynamic viscosity measured at 30 ° C. The dynamic viscosity can be measured using a BROOKFIELD viscometer as specified in the AFNOR standard NFT 76102 of May 1982.

DVB ≥ 10 hours leave enough room for manufacturers to implement the silicone coating at a rate and on an industrial scale, while placing the constraints at a tolerable level. Unfortunately the limitation imposed by the high crosslinking temperatures, with regard to the variety substrates that can be treated by non-stick silicone coating, constitutes a major handicap.

In addition, these high temperatures affect productivity and productivity. cost-effectiveness of coating treatments, due to the high cost of energy and necessary time.

To try to solve these difficulties, silicone systems without solvent for anti-adhesion, thermally crosslinkable and claiming a application performance called LTC (low temperature crosslinking) have been proposed.

These silicone thermal systems crosslink at temperatures included between 60 and 110 ° C. But unfortunately, the corollary of this decrease advantageous crosslinking temperature, is a significant drop in the DVB which can fall dramatically below 10 hours.

Such DVBs are incompatible with the constraints of use current industrial processes, suitable for anti-silicone coating treatment by coating. Indeed, the preparation of the mixture forming the silicone composition is generally performed in batch mode (BATCH). Now, in these techniques, the diet of the coating head from the mixing tank or tanks, involves necessarily stagnant times of the liquid silicone composition, before its application on the support. It is therefore easy to see that with short DVBs, problems of gelling and setting in mass are likely to intervene and significantly impair the quality of the coating.

Moreover, being forced to prepare relatively large quantities large quantities of BATCH, can cause serious economic damage that intervenes on the chain of coating, any incident of nature to interrupt the process.

In summary, the industrial silicone coating procedures are not not completely adapted to LTC non-stick silicone compositions, corresponding to what is currently best done in terms of crosslinkable silicone systems for anti-adhesion. Their maladjustment translated in terms of methodological heaviness, low productivity and cost-effectiveness, high cost and lower quality of anti-adhesive coatings obtained.

More generally, industrial applicators of the systems Non-stick silicones are waiting for a longer coating process universal with regard to the range of media likely to be coated with a coating obtained by thermal crosslinking or under the effect combination of heat and radiation, that is to say, allowing lower crosslinking temperatures, while preserving lifetimes for the non-crosslinked liquid silicone composition, which are of a acceptable level and compatible with industrial production requirements large scale and high speed.

It is also desirable to have silicone compositions crosslinkable, endowed with high kinetics of crosslinking, so as to achieve here again productivity and profitability gains.

The problem underlying the invention can therefore be summed up in the development of a compromise between the crosslinking temperature / crosslinking kinetics / bath lifetime parameters .

More pragmatically, the objective to be achieved would also be to to develop a clever and optimal mixing technique, with regard to industrial expectations for non-stick silicone coating at on an industrial scale.

Another obstacle to the optimization of industrial processes anti-adhesive silicone coating, which is related to the fact that these compositions require very precise and reliable dosages of the various ingredients. That is all the more complicated, as the relationships between these ingredients are very important: base POS with respect to the crosslinking agent and with respect to the catalyst.

• d'une part, de mettre en évidence qu'il convenait de simplifier la gestion des paramètres température de réticulation/cinétique de réticulation/DVB, en s'affranchissant de l'un de ces paramètres, à savoir la DVB,
• et d'autre part, d'avoir mis au point un procédé continu d'enduction faisant intervenir des étapes de dosage, de mélange homogène et d'alimentation de la tête d'enduction sur machine, lequel procédé permettant précisément, de manière surprenante et inattendue, de s'affranchir du paramètre DVB.

Faced with this problem, the inventors had the merit:

• on the one hand, to highlight that it was necessary to simplify the management of crosslinking temperature parameters / crosslinking kinetics / DVB, by avoiding one of these parameters, namely the DVB,
• and secondly, to have developed a continuous coating process involving steps of dosing, homogeneous mixing and feeding of the machine coating head, which process makes it possible, in a surprising manner and unexpectedly, to get rid of the DVB setting.

1. à mélanger en continu et en quantités dosées, notamment, le ou les POS A porteurs de groupements réactifs GRa, le ou les réticulants B porteurs de groupements réactifs GRb, et le catalyseur C ; en :

• réalisant éventuellement au moins un prémélange AB et/ou AC et/ou BC quand ce dernier est faisable,
• choisissant les conditions de mélange de manière que :
  • la Durée de Vie de Bain DVB soit inférieure à 10 H, de préférence à 4 H, et plus préférentiellement encore à 2 H,
  • l'homogénéité du bain soit telle que sa signature par calorimétrie différentielle par balayage DSC comprenne au moins un pic sensiblement gaussien présentant,
    une température T1 de début de pic,
    une température T2 de sommet de pic,
    une température T3 de fin de pic,
    ce pic étant caractérisé par :
  • - i - T3 ≤ 110° C, de préférence ≤ 90° C, et plus préférentiellement encore ≤ 80° C,
  • - ii - ΔT = T3 - T1 ≤ 30°C, de préférence ≤ 20° C et plus préférentiellement encore ≤ 15° C, T3 pouvant éventuellement ne pas satisfaire au paramètre -i- ci-dessus,
  et
  • iii - ΔT = ΔT ref ± 10° C,
    de préférence = ΔT ref ± 8° C,
    et plus préférentiellement = ΔT ref ± 4° C,
    ΔT ref correspondant à T3ref - T1ref, obtenu à partir du pic de signature DSC d'un mélange ABC de référence réalisé selon le protocole Pr défini ci-après dans le présent mémoire,
  • le débit de production du mélange homogène soit compris entre une valeur correspondant au taux de consommation du mélange sur le (ou les) site(s) d'enduction et une valeur déterminant la constitution d'une réserve-tampon,
    cette valeur du débit étant telle que la durée d séparant la mise en présence des composants A, B et C et le moment d'application de la composition ABC sur la bande support défilante soit inférieure ou égale à la DVB,

2. à acheminer, simultanément ou non, la composition directement du mélangeur vers le (ou les) site(s) d'enduction,

3. à enduire la bande-support défilante avec la composition,

4. à permettre à la réticulation thermique de se produire.

Thus, the present invention relates to a process for continuously coating a moving support strip in order to give it anti-adhesive properties, said coating being produced using a silicone composition comprising: at least one polyorganosiloxane At least one crosslinking agent B crosslinkable by hydrosilylation and / or by dehydrogenopolycondensation and an effective amount of catalyst C,
characterized in that it consists essentially of:

1. to mix continuously and in metered quantities, in particular, the A or POS A carrying reactive groups GRa, the B crosslinker (s) carrying reactive groups GRb, and the catalyst C; in :

• possibly realizing at least one premix AB and / or AC and / or BC when the latter is feasible,
• choosing the mixing conditions so that:
  • the life of DVB Bath is less than 10 H, preferably 4 H, and more preferably still 2 H,
  • the homogeneity of the bath is such that its differential scanning calorimetry signature DSC comprises at least one substantially Gaussian peak having,
    a temperature T1 of beginning of peak,
    a peak peak temperature T2,
    a temperature T3 of end of peak,
    this peak being characterized by:
  • - i - T3 ≤ 110 ° C, preferably ≤ 90 ° C, and more preferably still ≤ 80 ° C,
  • - ii - ΔT = T3 - T1 ≤ 30 ° C, preferably ≤ 20 ° C and more preferably still ≤ 15 ° C, T3 possibly not satisfying the parameter -i above,
  and
  • iii - ΔT = ΔT ref ± 10 ° C,
    preferably = ΔT ref ± 8 ° C,
    and more preferably = ΔT ref ± 4 ° C,
    ΔT ref corresponding to T3ref - T1ref, obtained from the DSC signature peak of a reference ABC mixture produced according to the Pr protocol defined hereinafter in the present document,
  • the production rate of the homogeneous mixture is between a value corresponding to the rate of consumption of the mixture on the coating site (s) and a value determining the constitution of a buffer reserve,
    this value of the flow being such that the duration d separating the placing in contact with the components A, B and C and the moment of application of the composition ABC on the moving support band is less than or equal to the DVB,

2. to convey, simultaneously or not, the composition directly from the mixer to the coating site (s),

3. to coat the moving support strip with the composition,

4. to allow thermal crosslinking to occur.

DSC analysis ("Differential Scanning Calorimetry") is carried out, in a manner known per se, using a METLER type TA 4000 device in using the following operating parameters: temperature: 10.0 ° C / min; mass of the test sample: 15 mg; work in a open crucible made of aluminum.

One of the essential principles governing the present invention is the combination of a precise dosing procedure and homogeneous mixing of compounds according to the non-stick coating silicone composition, by appropriate means and taking the decision to act on judiciously selected.

• la durée de vie de bain que l'on abaisse en deçà de 10 heures en jouant sur la nature et/ou les proportions des composants A, B, C et/ou de leurs possibles prémélanges,
• l'homogénéité du mélange que l'on maítrise au travers de la signature DSC, qui permet un étalonnage par rapport à un mélange de référence,
• et le débit de production de mélange homogène que l'on ajuste au taux de consommation avec ou sans formation de réserve tampon d'enduction.

These parameters are:

• the bath life that is lowered within 10 hours by varying the nature and / or proportions of the components A, B, C and / or their possible premixes,
• the homogeneity of the mixture, which is controlled through the DSC signature, which allows calibration with respect to a reference mixture,
• and the homogeneous mixing rate of production that is adjusted to the rate of consumption with or without forming a coating buffer.

The mixture thus measured and homogenized is directly sent to the coating head of the machine, so that only the amount of mixing necessary to feed the coating head (for example with a buffer reserve 10 to 30 min of consumption) is prepared.

• diminution de la température de réticulation des mélanges utilisés, d'où la possibilité d'enduire et de faire réticuler thermiquement des supports thermosensibles tels que par exemple les films PE, PP, PVC, PET ,
• possibilité de travailler avec des systèmes silicones dont la DVB est inférieure à 10 h et pour descendre à des valeurs aussi basses que celles inférieures à 2 H,
• préparation en continu de la quantité minimale de mélange nécessaire pour l'alimentation de la tête d'enduction, d'où réduction des pertes en cas d'incident interrompant le traitement d'enduction,
• fiabilité et précision du dosage des composants dans des rapports pouvant descendre jusqu'à 1 : 100 ou en dessous de 1 : 100 et cela même lorsqu'on opère avec de faibles débits ; la précision pouvant être de l'ordre de 2 %, d'où une régularité accrue de la qualité des produits finis,
• élimination des risques d'erreur de dosage provenant des méthodologies de préparation de mélange en BATCH par pesée manuelle,
• élimination des risques de pollution par des gels provenant des systèmes automatiques de préparation des mélanges en BATCH,
• amélioration de la productivité : diminution de temps de main d'oeuvre et des pertes matière,
• simplification du flux des matières premières silicones,
• facilité de préparation du mélange : moins de manutention et de travaux pénibles, donc risque d'incidents réduit,
• souplesse d'utilisation dans le changement de rapport de dosage et rapidité de mise en oeuvre sur machine : moins de perte de matière, rapidité dans les changements de fabrication,
• gain de temps d'opérateur sur machine pour des tâches non productives.

The advantages of the process according to the invention are numerous. We can mention in particular:

• reduction of the crosslinking temperature of the mixtures used, hence the possibility of coating and thermally cross-linking heat-sensitive substrates such as, for example, PE, PP, PVC, PET films;
• possibility to work with silicone systems with DVB less than 10 hours and to go down to values as low as those less than 2 hours,
• continuous preparation of the minimum amount of mixture necessary for feeding the coating head, thereby reducing losses in the event of an incident interrupting the coating treatment,
• reliability and accuracy of component dosing in ratios down to 1: 100 or below 1: 100 even when operating at low flow rates; the precision can be of the order of 2%, hence an increased regularity of the quality of the finished products,
• elimination of the risks of error of dosage resulting from the methods of preparation of mixture in BATCH by manual weighing,
• eliminating the risk of pollution by gels coming from automatic systems for preparing BATCH mixtures,
• productivity improvement: decrease in labor time and material losses,
• simplification of the flow of silicone raw materials,
• ease of preparation of the mixture: less handling and hard work, therefore reduced risk of incidents,
• flexibility of use in the change of ratio of dosing and speed of implementation on machine: less loss of material, speed in the changes of manufacture,
• time saving machine operator for unproductive tasks.

It is the merit of the inventors to have developed a methodology continuous coating, allowing the industrial use of crosslinking thermal silicones (polyaddition or dehydrogenopolycondensation) to such low temperatures and with DVBs as short as lower ones at 10 o'clock.

This innovation requires both the expertise of the chemistry of silicones and a control of accurate dosing technologies in reports e.g. in the range of 1: 100 and continuous intimate mixing of more products or less viscous that can be used at low flow.

Moreover, this method is of interest for the implementation of all silicone systems without solvent, with solvent, or emulsion type, thermally crosslinkable (polyaddition or dehydrogenopolycondensation) possibly associated with radiation, intended for layer coating thin non-stick coating on any medium: paper, polymer or textile.

Advantageously, the Pr protocol making it possible to establish the reference mixture ABC to obtain the comparative parameter ΔTref of the DSC peaks of the mixture, consists in mixing the same constituents A, B, C in the same proportions in order to produce in a container a mixture of 250 cm ³ , with gentle stirring using a rotary stirring at 1000 rpm for at least 15 min, at room temperature (25 ° C).

In practice, the buffer can be determined by both Contiguous cylinders, rotatable in opposite directions and constituting the head coating. This reserve is, for example, between 10 and 30 minutes consumption of the composition used for the coating.

The rate of coating consumption depends on the running speed of the support strip, the width and the nature of the latter (absorbency), as well as the viscosity of the crosslinkable silicone composition and the importance of the deposit (g / m ² ) desired.

In accordance with step 2 of the method, the routing of the composition at least partially mixed, towards the coating head is carried out simultaneously or not, insofar as it is possible to envisage the implementation of static or dynamic mixing means traversed by a flow of material, said flow being produced by feeding means or such as pumps, and in particular pumps volumetric, or pressure storage containers.

According to a preferred arrangement of the invention relating to step 1, implements mixing conditions A, B, C such as homogeneity obtained results in a DSC peak in which the parameters (i), (ii) and (3i) are cumulatively satisfied.

This corresponds to a silicone system LTC / FC, knowing that such If they are preferred according to the invention, they are not as exclusive other silicone systems crosslinking at higher temperature and / or a little less quickly.

To perfect the coating conditions, we make sure that the dynamic viscosity at 25 ° C, the homogeneous mixture is less than or equal to 10,000 mPa.s, preferably less than or equal to 1000 mPa.s.

• à prémélanger A et B et/ou A et C et/ou B et C lorsque c'est faisable,
• et/ou à mettre en oeuvre un prémélange AB.

According to a preferred embodiment of the invention, the continuous coating method comprises a preliminary step 0 consisting of:

• to premix A and B and / or A and C and / or B and C where feasible,
• and / or to implement a premix AB.

• à au moins l'un des composés de départ A, B, et C
• et/ou au prémélange AB et/ou AC et/ou BC lorsque ce dernier est faisable,
• ou dans le bain contenant les composés A,B et C,
  • au moins un inhibiteur D de réticulation (c'est en particulier le cas lorsque l'on met en oeuvre des systèmes silicones réticulant par hydrosilylation),
  • et/ou au moins un modulateur d'adhérence E,
  • et/ou au moins un autre composant F.

A, B, C are the basic compounds of the composition proper to the process according to the invention. But in reality, it is preferable to add other ingredients to them, by adopting or not the methodological variants of making premixes of these additional ingredients with compounds A, B, C. Thus, it is advantageous to incorporate:

• at least one of the starting compounds A, B, and C
• and / or premix AB and / or AC and / or BC when the latter is feasible,
• or in the bath containing compounds A, B and C,
  • at least one crosslinking inhibitor D (this is particularly the case when using crosslinking silicone systems by hydrosilylation),
  • and / or at least one adhesion modulator E,
  • and / or at least one other component F.

· lorsque la composition selon le procédé de l'invention renferme, à côté des composés A, B et C, les ingrédients optionnels D et/ou E et/ou F,

· l'analyse par DSC ainsi que le protocole Pr, dont on a parlé ci-avant, vont concerner alors le mélange constitué de A, B, C et de D et/ou E et/ou F.

It must be understood that:

When the composition according to the process of the invention contains, besides compounds A, B and C, the optional ingredients D and / or E and / or F,

The DSC analysis as well as the Pr protocol, referred to above, will then concern the mixture consisting of A, B, C and D and / or E and / or F.

• 1' - prémélange (étape 0) des composés A, B + éventuellement D et/ou E et/ou F ;
• 1 " - puis mélange homogène du prémélange (e.g. AB, ABD, ABDE, ABDEF, ABE, ABF, ABDF, ABEF) avec le composé C.

According to a still more preferred embodiment of the invention, it is ensured that step 1 breaks down as follows:

• Premixing (step 0) compounds A, B + optionally D and / or E and / or F;
• 1 "- then homogeneous mixture of the premix (eg AB, ABD, ABDE, ABDEF, ABE, ABF, ABDF, ABEF) with the compound C.

• les POS qui présentent, par molécule, au moins deux groupes GRa, situés dans la chaíne et/ou en bout(s) de chaíne, consistant chacun dans un groupe alcényle en C₂-C₁₀ lié au silicium, de préférence vinyle,
• et leurs mélanges,

   tandis que le réticulant B consiste dans au moins un POS présentant, par molécule, au moins deux et, de préférence, au moins trois groupes GRb consistant chacun en un atome d'hydrogène lié au silicium, situés dans la chaíne et/ou en bout(s) de chaíne ;
   A réagissant avec B par hydrosilylation.Without this being limiting, POS A is preferably selected;
in the group comprising:

• the POS which have, per molecule, at least two groups GRa, located in the chain and / or at the end (s) of chain, each consisting in a C ₂ -C ₁₀ alkenyl group bonded to silicon, preferably vinyl,
• and their mixtures,

while the crosslinking agent B consists of at least one POS having, per molecule, at least two and, preferably, at least three GRb groups each consisting of a hydrogen atom bonded to silicon, located in the chain and / or in the end (s) chain;
A reacting with B by hydrosilylation.

For such compounds A and B, it has been demonstrated that the GRb: GRa molar ratio should be advantageously in the meantime ranging from 1 to 5, preferably from 1.1 to 3 and even more preferably from 1.5 to 2.5.

This is the framework in which the skilled person is able to find the appropriate molar rations to respect the operating parameters of the invention as defined above and to apply them to the case of compounds A and B crosslinkable by hydrosilylation.

Examples of POS A are (dimethyl) polysiloxanes with ends dimethylvinylsilyl copolymers (methylvinyl) (dimethyl) polysiloxanes with trimethylsilyl ends, the (methylvinyl) (dimethyl) polysiloxane copolymers with dimethylvinylsilyl ends, cyclic (methylvinyl) polysiloxanes.

Examples of crosslinker B are dimethylhydrogensilyl-terminated (dimethyl) polysiloxanes, trimethylsilyl-terminated (methylhydrogen) polysiloxanes, trimethylsilyl-terminated (dimethyl) (methylhydrogen) -polysiloxane copolymers, cyclic (methylhydrogen) polysiloxanes and M 'resins. Q consisting of (CH ₃ ) ₂ HSiO _1/2 and SiO _{2 units}

The polyaddition silicone composition bases may comprise only linear POS, such as the one described in the U.S. Patent Nos. 3,229,172, 3,697,473, 4,340,709 or alternatively Branched or networked POS, for example that described in the patents U.S. 3,284,406, 3,434,366.

• les polydiorganosiloxanes portant au moins deux groupes GRa condensables ou hydrolysables, situés dans la chaíne et/ou en bout(s) de chaíne, consistant chacun dans un groupe OR lié au silicium ou R est un atome d'hydrogène ou un radical alkyle en C₁-C₆.
• et leurs mélanges ;

   tandis que le réticulant B est du type POS B porteur de GRb = H ;
   A réagissant avec B par déshydrogénopolycondensation ;
   et en ce que le ratio molaire GRb : GRa se situe dans l'intervalle allant de 1 à 5, de préférence 1 à 3.According to one variant, the POS A is selected from:

• polydiorganosiloxanes carrying at least two condensable or hydrolysable GRa groups, located in the chain and / or at the end (s) of the chain, each consisting of a silicon-bonded OR group or R is a hydrogen atom or a C-alkyl radical; ₁ -C ₆ .
• and their mixtures;

while the crosslinking agent B is of the POS B type bearing GRb = H;
Reacting with B by dehydrogenopolycondensation;
and in that the molar ratio GRb: GRa is in the range of 1 to 5, preferably 1 to 3.

Examples of POS A crosslinkable by dehydrogenopolycondensation are the (dimethyl) polysiloxanes with ends hydroxydimethylsilyl or with alkoxydimethylsilyl or dialkoxymethylsilyl ends with alkoxy being methyloxy, ethyloxy or propyloxy.

POS which may constitute compounds A and B of the systems by dehydrogenopolycondensation may also present a linear structure, possibly branched, cyclic or networked.

With regard to the effective amount of catalyst C with respect to other components A and B means a necessary C concentration and sufficient to allow crosslinking according to the kinetics required by the methodology according to the invention and to achieve the characteristics of use, expected in the application non-stick coating.

In the case of a silicone system crosslinking by hydrosilylation, all the conventional hydrosilylation catalysts can be implemented in the process according to the invention. In particular, catalysts based on platinum, including catalysts of the Karstedt type. Thus, the catalyst C of polyaddition is preferably selected from platinum and rodium compounds. We can in particular use the complexes (Karstedt) of platinum and a product described in US Pat. Nos. 3,159,601, 3,159,602, 3,220,972 and European Patents EP 0 057 459, EP 0 188 978 and EP 0 190 530, or the complexes (Karstedt) of platinum and of vinyl organositoxanes described in U.S. Patent Nos. 3,419,593, 3,715,334, 3,377,432 and 3,814,730.

To fix the ideas, we can indicate that it is preferable that the quantity or the concentration of C is between 10 and 250 ppm of catalyst taken from the metallic state, preferably from 30 to 200 ppm and more preferably still from 50 to 150 ppm, relative to the amounts of compounds A and possibly D and / or E, implemented.

The catalysts C used in the type of crosslinking by dehydrogenopolycondensation are either platinum-based catalysts such than those mentioned above, or the conventional catalysts of condensation composed of at least one metal belonging to the group of tin, the latter metal being particularly preferred. It can be for example dilaurate, dibutyl tin.

Catalyst C, when it is platinum-based, is used in the proportions indicated above, when it is based on tin, its quantity, expressed in ppm tin metal relative to the amounts of compounds A and optionally D and / or E, is between 1000 and 5000 and, preferably, between 2000 and 4000.

In the preferred variant of the invention, according to which an inhibitor D in a system where the crosslinking between A and B occurs at least partly by a mechanism of hydrosilylation, D inhibitors are favored selected from the group consisting of: α-acetylenic alcohols, azodicarboxylates, maleic esters, and mixtures thereof, trimethyl-3,7,11-dodecyne-1ol-3 (TMDDO) and ethynyl-cyclohexanol (ECH) being preferred.

As an example of a hydrosilylation reaction inhibitor D, likely to be employed, there may be mentioned those described in the patent application French No. 2,704,553 relating to long-chain α-acetylenic alcohols. The The content of this patent application is, moreover, fully incorporated into the presented by reference.

For Azodicarboxylate D-type inhibitors, reference should be made to European Patent Application No. 0 184 965 which describes in detail such polyaddition crosslinking reaction inhibitors. The content of this patent application is also fully included in this application by reference. As examples of inhibitory compounds of the azodicarboxylate type, mention may be made of ethyl azodicarboxylate.

For maleic-type D inhibitors, reference should be made to French Patent Application No. 2,456,767 which describes in detail such inhibitors. The content of this patent application is also fully included in the this request by reference. As an example of an inhibitor compound of this type, mention may be made of di-n-butyl maleate, diallyl maleate.

• les résines POS modulateurs à fonction Si alcényle qui sont décrites dans le demande de brevet français N° 2 704 553 (résines dites dans ce document , RM « Si alcényle ») ;
• les résines POS modulateurs à fonction SiH qui sont décrites dans la demande de brevet français N° 2 704 553 (résines dites dans ce document, RM « SiH ») ;
• les résines POS modulateur à fonction Si-OH, constituée d'au moins deux types de motifs siloxy différents « M » (R₃SiO_1/2), « Q » (SiO₂) et/ou « T » (RSiO_3/2) et éventuellement « D » (R₂SiO_2/2), les radicaux organiques étant identiques ou différents et représentant des groupes alkyle ou cycloalkyle en C₁-C₁₈ ou phényle, au moins 80 % molaire des radicaux organiques représentant un groupe méthyle, ladite résine contenant au moins 0,1 % molaire, de préférence de 0,5 à 5 % molaire de groupes hydroxyles liés au silicium avec un rapport nombre de motifs « M »/nombre de motifs « Q » et/ou « T » de 0,6-1, le nombre de motifs « D » éventuels étant de 0,5-10 pour 100 moles de résine ;
• les mélanges de deux ou de plus de deux des résines précitées entre elles ;
• les mélanges d'au moins une des résines précitées avec les solvants dits « réactifs » qui sont décrits dans la demande de brevet français N° 2 704 553. (étant rappelé que le contenu de cette demande de brevet N° 2 704 553 est inclus entièrement dans la présente demande par référence).

As another optional compound of the silicone composition specific to the process of the invention, namely the adhesion modulator E, it is preferably selected from the group of compounds formed by:

• the allyyl-function-modulating POS resins which are described in the French patent application No. 2,704,553 (resins referred to herein as "alkenyl");
• SiH-functional modulator POS resins which are described in French Patent Application No. 2,704,553 (resins referred to herein as "SiH");
• Si-OH modulator POS resins, consisting of at least two different types of siloxy units "M" (R ₃ SiO _1/2 ), "Q" (SiO ₂ ) and / or "T" (RSiO _{3 / 2} ) and optionally "D" (R ₂ SiO _2/2 ), the organic radicals being identical or different and representing C ₁ -C ₁₈ alkyl or cycloalkyl groups or phenyl, at least 80 mol% of the organic radicals representing a group methyl, said resin containing at least 0.1 mol%, preferably from 0.5 to 5 mol% of silicon-bonded hydroxyl groups with a ratio of number of "M" units / number of "Q" units and / or "T"units; Of 0.6-1, the number of possible "D" units being 0.5-10 per 100 moles of resin;
• mixtures of two or more of the abovementioned resins;
• mixtures of at least one of the abovementioned resins with the so-called "reactive" solvents which are described in the French patent application No. 2 704 553. (it being recalled that the content of this patent application No. 2 704 553 is included entirely in this application by reference).

• MD^ViQ où les groupes vinyles sont inclus dans les motifs D,
• MM ^ViQ où les groupes vinyles sont inclus dans une partie des motifs M,
• MD'Q où les atomes d'hydrogène liés au silicium sont inclus dans les motifs D,
• MM'Q où les atomes d'hydrogène liés au silicium sont inclus dans une partie des motifs M,
• MQ(OH) où les groupes hydroxyle liés au silicium sont inclus dans les motifs M.

As examples of resins forming part of the adhesion modulator E according to the present invention, mention may be made of the resins:

• MD ^Vi Q where the vinyl groups are included in the D patterns,
• MM ^Vi Q where the vinyl groups are included in part of the patterns M,
• MD'Q where the silicon-bonded hydrogen atoms are included in the D units,
• MM'Q where silicon-bonded hydrogen atoms are included in a part of the M units,
• MQ (OH) where the silicon-bonded hydroxyl groups are included in the M units.

(i) par un solvant organique aliphatique et/ou aromatique ne participant pas à la réaction, ce solvant étant de préférence celui dans lequel A et/ou B sont dissous pour constituer une solution qui représente la forme sous laquelle A et/ou B sont mis en oeuvre dans le procédé ;

(2i) et/ou par de l'eau dans le cas de la mise en oeuvre d'un système en émulsion.

As already indicated above, the mixture prepared according to the process of the invention may advantageously comprise at least one other component F consisting of:

(i) an aliphatic and / or aromatic organic solvent not participating in the reaction, this solvent being preferably that in which A and / or B are dissolved to form a solution which represents the form in which A and / or B are implemented in the process;

(2i) and / or with water in the case of the implementation of an emulsion system.

According to a preferred feature of the invention, the concentration of inhibitor D is less than or equal to 0.5% by weight, preferably 0.2% by weight. weight and more preferably still at 0.15% by weight, relative to amount of compounds A and possibly E.

The possibility of using such low D inhibitor concentrations is a great advantage especially on the economic level. This advantage is good obviously inherent in the continuous process according to the invention.

The presence of an additional additive of the organic solvent type, does not not participating in the reaction, preferably aliphatic or aromatic, is relate to the possibility offered by the invention to implement the starting compounds in solution form. Indeed, POS resins A or B, even the compounds C, D and E can be fed dosed, mixed and delivered to the coating head as a solution.

Alternatively, the compounds A, B, C, D, E can be employees in emulsion form.

According to an advantageous arrangement of the invention, so that the admission in measured quantities of the constituents A, B, C possibly D and / or E and / or F, at the level of the possible sites of premix and / or the site (s) of mixing C with the others components, is done sequentially and iteratively.

Thus, in the case where it is, for example, in accordance with a step 1, of a premix of the compounds A, B, D, it is expected that circuit feeding with these 3 compounds, operates successively according to for example A / B / D, or AD / B / A, repeated throughout the operation continuous process.

According to another characteristic of the invention, the operations of mixing and possibly premixing are subdivided into a step of upstream mixing and a downstream mixing step.

The upstream mixing step corresponds to a contacting of everything or part of the compounds while the downstream mixing step is, in fact, a intimate and homogeneous mixing operation of the above-mentioned compounds with addition eventual missing compound (s).

In practice, the organization of the flow of material according to sequences repeated several strata of each compound for example A, B, D or A, B, D, C advantageously finds its place upstream of the site or sites of premix or downstream mixing.

As already mentioned above, one of the key elements of the the invention relates to the continuous dosing of the compounds of the composition. For carry out this operation, it is used in a privileged way for each component A, B, C, optionally D and / or E and / or F of the composition, to dosing means, in particular volumetric, capable of ensuring the supply of quantity of each of them and, at least partially, their circulation in a continuous flow, all along the operating line.

With regard to mixing operations and even possible premixes, it is advantageous to use static or dynamic mixing means.

· la vitesse de défilement de la bande-support,

· le taux de consommation de la composition à l'enduction,

· la durée de vie de bain DVB,

· les débits d'alimentation des constituants A à F au niveau des sites de mélange voire de prémélange,

· les débits en sortie de mélange voire de prémélange,

· la vitesse du flux de mélange voire du flux du prémélange,

· la durée séparant la mise en présence de C avec les constituants nécessaires à la réaction et le dépôt du mélange sur la bande-support.

The inventors have selected, in addition to the main parameters of this method mentioned above, other parameters which it is advisable to take into account to ensure a smooth process. Thus, advantageously, the parameters to be considered also for premixing and / or mixing are:

· The speed of travel of the support strip,

· The rate of consumption of the composition to the coating,

· The DVB bath lifespan,

The feed rates of the constituents A to F at the mixing or even premixing sites,

The flow rates at the outlet of the mixture or premix,

· The speed of the mixture flow or even of the premix flow,

The time separating the introduction of C with the constituents necessary for the reaction and the deposition of the mixture on the support strip.

· des moyens de dosage notamment volumétrique des composants A, B, C, éventuellement D et/ou E et/ou F,

· d'éventuels moyens de prémélange des composants autre que C,

· des moyens de mélange homogène des composants A, B, C, éventuellement D et/ou E et/ou F,

· au moins un organe d'enduction de la bande support défilante,

· des moyens d'acheminement du mélange homogène du ou des sites (moyens) de mélange vers l'organe d'enduction, et éventuellement du ou des sites (moyens) de prémélange vers les moyens de mélange,

· et des moyens de chauffage de la bande-support enduite, ces moyens étant de préférence constitués par au moins un four-tunnel.

According to another of these aspects, the present invention relates to a device in particular for implementing the method as defined above. This device is characterized in that it comprises:

· Dosing means including volumetric component A, B, C, optionally D and / or E and / or F,

· Any means of premixing components other than C,

· Means for homogeneously mixing components A, B, C, optionally D and / or E and / or F,

At least one coating member of the moving support strip,

Means for conveying the homogeneous mixture from the mixing site (s) to the coating member, and optionally from the premixing site (s) to the mixing means,

And means for heating the coated support strip, these means being preferably constituted by at least one tunnel furnace.

Advantageously, the possible premixing means comprise at least one upstream premixing chamber and premixing means downstream static, and the homogeneous mixing means comprise at least one upstream mixing chamber and downstream static mixing means.

As a coating member, all the systems can be used capable of coating in a thin layer; for example, the systems: "size press ", air knife, Meyer bar," direct engraving "head," multicylinder "head. Advantageously, the coating member is constituted by a head "direct etching" (or engraved cylinder) or by a "multicylinder" head, which are very widespread in the paper industry.

The structure and operation of this device will be better understood in the light of the description which follows, by way of non-limiting example, of a mode of preferred embodiment of said device as well as examples of implementation of the continuous coating method according to the invention, using said device.

The description of the device is made with reference to the attached Fig.1 which shows a block diagram of the preferred embodiment of the device according to the invention.

The latter comprises means 1 for volumetric dosing of compounds A, B, D and C which are, respectively, a POS, a crosslinking agent, an inhibitor and a catalyst, for example platinum or tin depending on whether the systems are of the polyaddition type. or dehydrogenopolycondensation.

The device also comprises means 2 for premixing components other than C, means 3 for homogeneously mixing constituents A, B, D, C, a coating member 4, means for conveying premix 5 and the homogeneous mixture. premixing and mixing sites respectively to the coating member 4 , and means 6 for heating the moving strip 7 .

Metering means 1 are, for example, volume meters, that is to say mechanical gear elements, allowing accurate measurement of a volume of product. Each volume meter 1 is arranged between a feed source of compounds A, B, D or C and the premixing means 2 , with regard to the constituents A, B, D, and the means 3 of homogeneous mixing, for this purpose. which concerns catalyst C.

Each volume meter 1 behaves like a metering pump which takes the appropriate amount of compounds to inject it into the mixing circuit. A solenoid valve 8 is provided on the connection connecting each volume meter 1 to the means 2 and 3 premixing and mixing respectively.

The latter respectively comprise an upstream premixing chamber 2.1 and upstream mixing chamber 3.1, each connected by a pipe 5 forming the conveying means, to a downstream static premix chamber 2.2 and to a downstream static mixing chamber 3.2, respectively.

The upstream 2.1 and downstream 2.2 chambers allow the premixing of the compounds A, B, D whereas the upstream 3.1 and downstream 3.2 chambers allow the homogeneous and intimate mixing of the premix A, B, D with the catalyst C.

Each upstream chamber 2.1 and 3.1 is a member: (i) static mixing known per se, constituted, for example, by a cylinder comprising coaxial O-channels, and (2i) transit of the introduced materials. Each channel can be equipped with static stirring palettes. Such an organ makes it possible to ensure the first contact of the products.

The downstream chambers 2.2 and 3.2 are, eg static mixers of a type known per se, constituted by a hollow cylinder, provided inside mixing stators (palettes) and through which, the silicone composition A, B, D or A, B, D, C is capable of migrating while being stirred and mixed, in a homogeneous and intimate manner.

An electrovalve 8 is provided on the pipe 5 between the downstream chamber 2.2 and the upstream chamber 3.1.

The static mixers used in this device are arranged in line in the conveying means 5 (channel) constituted, for example, by a hose.

Advantageously, the coating member 4 is a "multi-cylinder" head constituted by two smooth cylinders 9.1 and 9.2 defining the coating head facing which opens the end of the conveying means 5. The cylinders 9.1 and 9.2 are contiguous and are rotatable in opposite directions. The member 4 also comprises a relay cylinder 10 coupled to the pair of rolls 9.1 and 9.2 and ensuring the connection thereof with a pair of rolls 11.1 and 11.2 , in the air gap of which the carrier strip 7 circulates to be optionally coated with silicone composition A, B, D, C crosslinking. This coating member 4 is known per se.

According to a preferred characteristic of the invention, the end of the conveying means 5 of the intimate mixture is subdivided into two branches 12.1 and 12.2 which make it possible to provide a feed at two points of the metering rolls 9.1 and 9.2, with the mixture Homogeneous homogeneous A, B, D, C crosslinkers. Preferably, each of these two feed points is disposed adjacent an end of the injection head 9.1 / 9.2. According to variants, it could be provided several injection points arranged throughout the air gap metering rolls 9.1 and 9.2 .

These define a buffer pool of composition intimately and homogeneously mixed A, B, D, C. With the cylinder 10 and the press 11.1 / 11.2, this composition is transferred and applied on the support strip 7, which scrolls to a given speed in the direction indicated by the arrows on the drawing. This band coated on one side then passes through the heating means 6 which are advantageously a tunnel-oven, of the type known in the technical field considered.

The volume meters 1, the solenoid valves 8, the coating member 4, the moving strip 7, and the tunneling furnace 6 can be slaved to a central control and calculation unit, allowing the programming of the dosing operating parameters. , flow rate, reagent bath consumption rate and crosslinking temperature, among others.

According to variants of the invention, it could be provided in addition thermal means of crosslinking, other means of activating the crosslinking, for example actinic irradiation or electron beam.

By way of non-limiting example of dosing and mixing means continuous device that can be used in the device according to the invention, mention may be made of those described in French Patent Application No. 2,508,635 and in the model German Utility No. 296 06 710 (DOPAG).

EXAMPLES EXAMPLE 1: CONTINUOUS COATING TESTS OF AN ANTI-ADHERENT SILICONE COMPOSITION THERMALLY HEATABLE BY HYDROSILYLATION OF A REAGENT GROUP POS GRa = SI-VI , USING A REACTIVE GROUPING POS GRb = SI-H 1.1. Material and raw materials

The device used is that shown in Figure 1 and described above. More precisely, in this example, a VOLUMIX® type dosing and continuous mixing device sold by the company DOPAG is used.

The coating member is constituted by a coating head five cylinders.

The tunnel furnace has the following characteristics: hot air blast by nozzle on the coated side following 3 zones of 2 meters long each, with an air flow of 1800 m ³ per hour and per zone.

• prémélange composés A et D : POS A formé par une huile consistant dans un copolymère (méthylvinyl)(diméthyl)polysiloxane à extrémités diméthylvinylsilyle contenant 0,031 mole de vinyle/100 g, cette huile étant chargée à hauteur de 0,15 % en poids d'inhibiteur D constitué par un alcool α-acétylénique : le triméthyl 3-7-11 dodécyne-1ol-3 (TMDDO) ;
• composé A : il s'agit de l'huile POS vinylée mise en oeuvre pour préparer le prémélange AD ;
• réticulant B : mélange comprenant 70 % en poids de POS du type (méthylhydrogéno)polysiloxanes à extrémités triméthylsilyle et de 30 % en poids de résine M'Q constituée de motifs (CH₃)₂ HSiO_1/2 et SiO₂, ledit mélange contenant 1,35 moles de fonctions SiH pour 100 g ;
• catalyseur C : catalyseur au platine du type Karsdedt constitué par une solution à 2000 ppm de platine métal dans une huile polydiméthyl-siloxane à extrémités diméthylvinylsilyle ; ladite solution contenant 0,041 mole de vinyle/100 g.

The compounds A, B, D, C used are the following:

• compound A and D: POS A premix consisting of an oil consisting of a dimethylvinylsilyl-terminated (methylvinyl) (dimethyl) polysiloxane copolymer containing 0.031 mole of vinyl / 100 g, this oil being filled to a level of 0.15% by weight of inhibitor D constituted by an α-acetylenic alcohol: trimethyl 3-7-11 dodecyne-1ol-3 (TMDDO);
• compound A: it is the vinylated POS oil used to prepare the premix AD;
• crosslinking agent B: a mixture comprising 70% by weight of the trimethylsilyl-type (methylhydrogen) polysiloxane-type POS and 30% by weight of M'Q resin consisting of (CH ₃ ) ₂ HSiO _1/2 and SiO _{2 units} , said mixture containing 1.35 moles of SiH functions per 100 g;
• Catalyst C: Karsdedt platinum catalyst consisting of a 2000 ppm solution of platinum metal in a dimethylvinylsilyl-terminated polydimethylsiloxane oil; said solution containing 0.041 mole of vinyl / 100 g.

The device therefore comprises 4 power sources constituting the composition, namely: premix AD, POS B, POS A, and catalyst C.

1.2 Calibration of the volume meters:

(AD + B + A) : C → 100 parties poids : 6 parties poids ; soit 120 ppm de Pt par rapport à A + D.

The volume meters 1 assigned to the supply sources AD, B and A on the one hand and the catalyst supply source C, on the other hand, are adjusted so that the proportions used are as follows:

(AD + B + A): C → 100 parts weight: 6 parts by weight; ie 120 ppm of Pt relative to A + D.

AD : A → 66 parties en poids : 33 parties poids,

(AD + A) : B → 100 parties poids : 4,5 parties poids.

In the same way the volume meters 1 corresponding to AD, B and A are adjusted so that the proportions between these constituents are as follows:

AD: A → 66 parts by weight: 33 parts by weight,

(AD + A): B → 100 parts weight: 4.5 parts weight.

With these proportions: the molar ratio SiH: SiVinyl is equal to 1.8; the amount of inhibitor D is equal to 0.10% relative to the total mass of A.

We still find that the DVB of the mixture is only 35 min.

1.3. Other settings

Débit de sortie du mélangeur : 51 g/min ;

Capacité de la réserve tampon de l'organe d'enduction : 200g ;

Taux de consommation de la composition réticulante : 3 kg /heure ;

Vitesse de défilement de la bande : 150 mètres/min ;

Gradiant de température dans le four tunnel : 1ère zone : 110° C, 2ème zone : 100° C et 3ème zone : 100° C.

The following parameters are also set as follows:

Mixer output flow: 51 g / min;

Buffer capacity of the coating member: 200g;

Consumption rate of the crosslinking composition: 3 kg / hour;

Tape speed: 150 meters / min;

Temperature gradient in the tunnel kiln: 1st zone: 110 ° C, 2nd zone: 100 ° C and 3rd zone: 100 ° C.

1.4. Operation

The device is put into operation and the coating head 5 cylinders is fed continuously for 3 hours with the product mix AD, B, A and C. The paper coated with this coating member is a paper of glassine type. The deposit is made at a rate of 1 g / m2. It's cross-linked online by passage in a tunnel oven, at a temperature of about 100 ° C, the speed scrolling speed of 150 m / min.

This continuous operation was carried out without any significant problem. In especially no gelation. The quality of the non-stick coating obtained is quite satisfactory.

The supply of compounds AD, B and A is ensured by the meters and / or by a pump for example pneumatic and / or providing the pressurization of the reservoirs constituting the sources of various constituents.

The setting of the opening of the electro-valves 8 is programmed so that the feed of the premixing means 2 and the mixing means 3 is done according to iterative sequences AD / B / A on the one hand and ADB / C on the other hand share respectively.

The programming of the control unit obviously integrates variables or parameters for setting the volume meters and solenoids.

1.5. Process evaluation

• Température T1 de début de pic : 60,5° C,
• Température T2 de sommet de pic : 70,3° C,
• Température T3 de fin de pic : 80,4° C,
• Δ T = T3-T1 : 19,9° C.

The characterization of the homogeneous mixture obtained from the ingredients A, B, D, C is carried out by DSC differential thermal analysis using a METLER type TA 4000 apparatus: the curve given in FIG. 2 gives access to the values following (also given by the device):

• T1 temperature of beginning of peak: 60,5 ° C,
• T2 peak peak temperature: 70.3 ° C,
• T3 end of peak temperature: 80.4 ° C,
• ΔT = T3-T1: 19.9 ° C.

• Δ T réf = 18,7° C.
• Δ T = ΔT réf + 1,2° C.

We also find:

• Δ T ref = 18.7 ° C.
• ΔT = ΔT ref + 1.2 ° C.

We also appreciate the visual quality of the mixture obtained from the ingredients A, B, D, C having taken care to initially stain the catalyst C. It is observed that the result obtained is satisfactory since the color of the mixture is homogeneous.

EXAMPLE 2 TESTS AT DIFFERENT CONCENTRATIONS IN INHIBITOR D

The conditions are the same as in Example 1 above except for the parameters given in Table 1 below.

Comments:

Highly reactive silicone systems can be used with very short DVB, leading to a final product meeting the requirements required.

Claims (9)

1. Process for the continuous coating of a travelling support strip in order to give it non-stick properties, the said coating being carried out using a silicone composition comprising at least one polyorganosiloxane A bearing reactive groups RGa, at least one curing agent B bearing reactive groups RGb and which can be cured by hydrosilylation or by dehydrogenopolycondensation, an effective amount of catalyst C, and optionally at least one cure inhibitor D and/or at least one adhesion modifier E and/or at least one other constituent F,
   the said process essentially consisting of the following steps:

   0) the continuous preparation of at least one premix AB and/or AC and/or BC when the latter is feasible, the said premixing taking place for the components other than C by means of at least one upstream premixing chamber (2 ₁ ) and downstream static premixing means (2 ₂ );

   1) the continuous preparation of a homogeneous compound of the constituents A, B and C, the said homogeneous compound being produced, in the case of the components A, B, C, optionally D and/or E and/or F by means of an upstream mixing chamber (3 ₁ ) and downstream static mixing means (3 ₂ ),
   steps 0) and 1) being carried out:

   (j) by choosing the nature and the proportions of the constituents A, B and C in such a way that:

   the dynamic viscosity at 25°C of the homogeneous compound is less than or equal to 10,000 mPa.s; and

   the POS A is selected from the group comprising:

   POSs that contain, per molecule, at least two groups RGa, located in the chain and/or at the chain end(s), each consisting of a C₂-C₁₀-alkenyl group linked to the silicon;

   and mixtures thereof,

   while the curing agent B consists of at least one POS containing, per molecule, at least two groups RGb, each consisting of a hydrogen atom linked to the silicon, located in the chain and/or at the chain end(s), A reacting with B by hydrosilylation and the molar ratio RGb/RGa is within the range from 1 to 5;

   (2j) by optionally incorporating at least one constituent D and/or E and/or F into at least one of the constituents A, B, C, into the premix or into the bath containing the constituents A, B and C; and

   (3j) by employing premixing and homogeneous compounding conditions such that:

   the bath life BL, which is the time needed to double the dynamic viscosity measured at 30°C, is less than 4h;

   the bath homogeneity is such that its DSC (differential scanning calorimetry) signature comprises at least one Gaussian peak having, a peak start temperature T1, a peak summit temperature T2, and a peak end temperature T3,
      this peak being characterized by:

   (i) T3 ≤ 110°C,

   (ii) ΔT = T3 - T1 ≤ 30°C,
   and

   (iii) ΔT = ΔT_ref ± 10°C,
   ΔT_ref corresponding to T3_ref-T1_ref, obtained from the DSC signature peak of a reference compound consisting of A, B, C and optionally D and/or E and/or F produced according to the protocol Pr for establishing the reference compound ABC in order to arrive at the comparative parameter ΔT_ref of the DSC peaks of the compound, which protocol consists in mixing the same constituents A, B, C in the same proportions in order to prepare, in a container, a compound of 250 cm³ in volume, with moderate stirring using an impeller rotating at 1000 rpm for at least 15 min, at room temperature (25°C); and

   the production flow rate of the homogeneous compound is between a value corresponding to the rate of consumption of the compound on the coating site(s) and a value which determines the constitution of a buffer reserve, this flow rate value being such that the time t separating the time at which the components A, B and C and optionally D and/or E and/or F are brought together and the time of application of the homogeneous compound to the travelling support strip is less than or equal to the BL; then

   2) conveying, simultaneously or otherwise, the homogeneous compound directly from the mixer to the coating site(s);

   3) coating the travelling support strip with the composition; and

   4) a step of allowing the heat curing to take place.
2. Process according to Claim 1, in which:

   the POS A is selected from the group comprising:

   polydiorganosiloxanes bearing at least two condensable or hydrolysable groups RGa, which are located in the chain and/or at the chain end(s), each consisting of an OR group linked to the silicon, where R is a hydrogen atom or a C₁-C₆-alkyl radical; and

   mixtures thereof; and

   the curing agent B is of the POS B type carrying RGb=H;

   where A reacts with B by dehydrogenopolycondensation and the molar ratio RGb/RGa is in the interval from 1 to 5.
3. Process according to either one of Claims 1 and 2, characterized in that the crosslinking between A and B takes place at least partly according to a hydrosilylation mechanism and in that the inhibitor D is chosen from the group comprising: α-acetylenic alcohols, azodicarboxylates, maleic esters and mixtures thereof.
4. Process according to any one of Claims 1 to 3, characterized in that at least one adhesion modifier E is used, this being selected from the group of compounds below:

   POS modifying resins containing Si-alkenyl functions;

   POS modifying resins containing an SiH function;

   POS modifying resins containing an Si-OH function, consisting of at least two different types of siloxy units, namely "M" (R₃SiO_1/2), "Q" (SiO₂) and/or "T" (RSiO_3/2) and optionally "D" (R₂SiO_2/2), the organic radicals being identical or different and representing C₁-C₁₈-alkyl or cycloalkyl groups or phenyl groups, at least 80 mol% of the organic radicals representing a methyl group, the said resin containing at least 0.1 mol% of hydroxyl groups attached to the silicon with a number of "M" units/number of "Q" and/or "T" units ratio of 0.6-1, the number of optional "D" units being 0.5-10 per 100 mol of resin;

   mixtures of two or more than two of the abovementioned resins with each other;

   or mixtures of at least one of the abovementioned resins with so-called "reactive" solvents.
5. Process according to any one of Claims 1 to 4, characterized in that the compound prepared comprises at least one other component F consisting:

   (i) of an aliphatic and/or aromatic organic solvent which does not take part in the reaction, this solvent preferably being the one in which A and/or B are dissolved to make a solution which represents the form in which A and/or B are used in the process;

   (ii) and/or of water.
6. Process according to any one of Claims 1 to 5, characterized in that provision is made such that the admission of metered amounts of the constituents A, B, C, optionally D and/or E and/or F, into the site(s) for premixing and/or the site(s) for mixing C with the other components is carried out in a sequenced and repetitive manner.
7. Process according to any one of Claims 1 to 6, characterized in that, for each constituent A, B, C, optionally D and/or E and/or F of the composition, volumetric metering means are used which are capable of ensuring the supply of metered amounts of each of these constituents, as well as, at least partially, their circulation in a continuous flow, along the entire length of the operating line.
8. Device for carrying out the process according to any one of Claims 1 to 7, characterized in that it comprises:

   · means (1) for metering the components A, B, C, optionally D and/or E and/or F;

   · means (2) for premixing the components other than C;

   · means (3) for homogeneously mixing the components A, B, C, optionally D and/or E and/or F;

   · at least one member (4) for coating the travelling support strip (7);

   · means (5) for conveying the homogeneous compound from the mixing site(s) (means) to the coating member, and from the premixing site(s) (means) to the mixing means; and

   · means (6) for heating the coated support strip (7).
9. Device according to Claim 8, characterized in that the premixing means (2) comprise at least one upstream premixing chamber (2 ₁ ) and downstream static premixing means (2 ₂ ), and in that the homogeneous mixing means (3) comprise at least one upstream mixing chamber (3 ₁ ) and downstream static mixing means (3 ₂ ).

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